libvips/libsrc/arithmetic/im_min.c

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/* @(#) Function to find the minimum of an image. Works for any
* @(#) image type. Returns a double.
* @(#)
* @(#) int im_min(in, min)
* @(#) IMAGE *in;
* @(#) double *min;
* @(#)
* @(#) Returns 0 on success and -1 on error
*
* Copyright: 1990, J. Cupitt
*
* Author: J. Cupitt
* Written on: 02/05/1990
* Modified on : 18/03/1991, N. Dessipris
* 7/7/93 JC
* - complex case fixed
* - im_incheck() call added
* 20/6/95 JC
* - now returns double
* - modernised a little
* - now returns min square amplitude rather than amplitude for complex
* 9/5/02 JC
* - partialed, based in im_max()
* 3/4/02 JC
* - random wrong result for >1 thread :-( (thanks Joe)
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <assert.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Per-call state.
*/
typedef struct _MinInfo {
/* Parameters.
*/
IMAGE *in;
double *out;
/* Global min so far.
*/
double value;
int valid; /* zero means value is unset */
} MinInfo;
/* Per thread state.
*/
typedef struct _Seq {
MinInfo *inf;
double value;
int valid; /* zero means value is unset */
} Seq;
/* New sequence value.
*/
static void *
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start_fn( IMAGE *im, void *a, void *b )
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{
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MinInfo *inf = (MinInfo *) a;
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Seq *seq = IM_NEW( NULL, Seq );
seq->inf = inf;
seq->valid = 0;
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return( seq );
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}
/* Merge the sequence value back into the per-call state.
*/
static int
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stop_fn( void *vseq, void *a, void *b )
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{
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Seq *seq = (Seq *) vseq;
MinInfo *inf = (MinInfo *) a;
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if( seq->valid ) {
if( !inf->valid )
/* Just copy.
*/
inf->value = seq->value;
else
/* Merge.
*/
inf->value = IM_MIN( inf->value, seq->value );
inf->valid = 1;
}
im_free( seq );
return( 0 );
}
/* Loop over region, adding to seq.
*/
static int
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scan_fn( REGION *reg, void *vseq, void *a, void *b )
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{
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Seq *seq = (Seq *) vseq;
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Rect *r = &reg->valid;
IMAGE *im = reg->im;
int le = r->left;
int to = r->top;
int bo = IM_RECT_BOTTOM(r);
int nel = IM_REGION_N_ELEMENTS( reg );
int x, y;
double m;
#ifdef DEBUG
printf( "im_min: left = %d, top = %d, width = %d, height = %d\n",
r->left, r->top, r->width, r->height );
#endif /*DEBUG*/
#define loop(TYPE) { \
m = *((TYPE *) IM_REGION_ADDR( reg, le, to )); \
\
for( y = to; y < bo; y++ ) { \
TYPE *p = (TYPE *) IM_REGION_ADDR( reg, le, y ); \
\
for( x = 0; x < nel; x++ ) { \
double v = p[x]; \
\
if( v < m ) \
m = v; \
} \
} \
}
#define complex_loop(TYPE) { \
TYPE *p = (TYPE *) IM_REGION_ADDR( reg, le, to ); \
double real = p[0]; \
double imag = p[1]; \
\
m = real * real + imag * imag; \
\
for( y = to; y < bo; y++ ) { \
TYPE *p = (TYPE *) IM_REGION_ADDR( reg, le, y ); \
\
for( x = 0; x < nel * 2; x += 2 ) { \
double mod; \
\
real = p[x]; \
imag = p[x + 1]; \
mod = real * real + imag * imag; \
\
if( mod < m ) \
m = mod; \
} \
} \
}
switch( im->BandFmt ) {
case IM_BANDFMT_UCHAR: loop( unsigned char ); break;
case IM_BANDFMT_CHAR: loop( signed char ); break;
case IM_BANDFMT_USHORT: loop( unsigned short ); break;
case IM_BANDFMT_SHORT: loop( signed short ); break;
case IM_BANDFMT_UINT: loop( unsigned int ); break;
case IM_BANDFMT_INT: loop( signed int ); break;
case IM_BANDFMT_FLOAT: loop( float ); break;
case IM_BANDFMT_DOUBLE: loop( double ); break;
case IM_BANDFMT_COMPLEX: complex_loop( float ); break;
case IM_BANDFMT_DPCOMPLEX: complex_loop( double ); break;
default:
assert( 0 );
}
if( seq->valid ) {
seq->value = IM_MIN( seq->value, m );
}
else {
seq->value = m;
seq->valid = 1;
}
return( 0 );
}
int
im_min( IMAGE *in, double *out )
{
MinInfo inf;
inf.in = in;
inf.out = out;
inf.valid = 0;
if( im_pincheck( in ) )
return( -1 );
if( in->Coding != IM_CODING_NONE ) {
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im_error( "im_min", "%s", _( "not uncoded" ) );
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return( -1 );
}
if( im_iterate( in, start_fn, scan_fn, stop_fn, &inf, NULL ) )
return( -1 );
*out = inf.value;
return( 0 );
}